1. Technical Field
The present invention relates to the field of electrostatic protection circuit design, and more specifically, to the structure of bipolar transistor and thyristor (or known as Silicon-controlled Rectifier) in electrostatic protection circuit and the method of manufacturing the same.
2. Description of Related Art
Electrostatic discharge (known as ESD) is an event frequently occurred to integrated circuit chip. The quantity of electrical charge from this event may be transferred into the integrated circuit through the I/O pin of the integrated circuit chip within a very short period, which may damage the internal circuit of the integrated circuit. To solve this problem, a protection circuit is generally mounted between internal circuit and I/O pin. The protection circuit is activated before the pulse arrives at the internal circuit and rapidly eliminates the over high voltage to avoid the damage caused by the ESD event.
Refer to FIG. 1 and FIG. 2 for the structures of a typical discharge cell bipolar transistor and a thyristor in electrostatic protection circuit.